iOS 如何获取本地视频的参数信息

 NSArray <AVAssetTrack *> *videoTracks = [asset tracksWithMediaType:AVMediaTypeVideo];
if (0 == videoTracks.count) {
    return ;
}
AVAssetTrack *videoTrack = [videoTracks firstObject];

CMFormatDescriptionRef formatDescription = NULL;
NSArray *formatDescriptions = [videoTrack formatDescriptions];
if ([formatDescriptions count] > 0) {
    formatDescription = (__bridge CMFormatDescriptionRef)[formatDescriptions objectAtIndex:0];
}

// 数据速率
float bps = [videoTrack estimatedDataRate];
// 分辨率
float fps = [videoTrack nominalFrameRate];